126 lines
5.1 KiB
HTML
126 lines
5.1 KiB
HTML
<head>
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<title>exits(3) - Plan 9 from User Space</title>
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<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
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<body bgcolor=#ffffff>
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=10><td>
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<tr><td width=20><td>
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<tr><td width=20><td><b>EXITS(3)</b><td align=right><b>EXITS(3)</b>
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<tr><td width=20><td colspan=2>
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<br>
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<p><font size=+1><b>NAME </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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exits, _exits, atexit, atexitdont, terminate – terminate process,
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process cleanup<br>
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</table>
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<p><font size=+1><b>SYNOPSIS </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>#include <u.h><br>
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#include <libc.h>
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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</font></tt>
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<tt><font size=+1>void _exits(char *msg)<br>
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void exits(char *msg)<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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</font></tt>
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<tt><font size=+1>int atexit(void(*)(void))<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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</font></tt>
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<tt><font size=+1>void atexitdont(void(*)(void))<br>
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</font></tt>
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</table>
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<p><font size=+1><b>DESCRIPTION </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<i>Exits</i> is the conventional way to terminate a process. <i>_Exits</i> also
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terminates a process but does not call the registered <i>atexit</i> handlers
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(<i>q.v.</i>). They can never return.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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<i>Msg</i> conventionally includes a brief (maximum length <tt><font size=+1>ERRLEN</font></tt>) explanation
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of the reason for exiting, or a null pointer or empty string to
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indicate normal termination. The string is passed to the parent
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process, prefixed by the name and process id of the exiting process,
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when the parent does a <a href="../man3/wait.html"><i>wait</i>(3)</a>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Before calling <i>_exits</i> with <i>msg</i> as an argument, <i>exits</i> calls in
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reverse order all the functions recorded by <i>atexit</i>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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<i>Atexit</i> records <i>fn</i> as a function to be called by <i>exits</i>. It returns
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zero if it failed, nonzero otherwise. A typical use is to register
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a cleanup routine for an I/O package. To simplify programs that
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fork or share memory, <i>exits</i> only calls those <i>atexit</i>-registered
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functions that were registered by the same process as that calling
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<i>exits</i>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Calling <i>atexit</i> twice (or more) with the same function argument
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causes <i>exits</i> to invoke the function twice (or more).
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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There is a limit to the number of exit functions that will be
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recorded; <i>atexit</i> returns 0 if that limit has been reached.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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<i>Atexitdont</i> cancels a previous registration of an exit function.<br>
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</table>
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<p><font size=+1><b>SOURCE </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>/usr/local/plan9/src/lib9/atexit.c<br>
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/usr/local/plan9/src/lib9/_exits.c<br>
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</font></tt>
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</table>
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<p><font size=+1><b>SEE ALSO </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<a href="../man2/fork.html"><i>fork</i>(2)</a>, <a href="../man3/wait.html"><i>wait</i>(3)</a><br>
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</table>
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<p><font size=+1><b>BUGS </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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Because of limitations of Unix, the exit status of a process can
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only be an 8-bit integer. Exit status 0 is used for empty exit
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messages, and 1 for non-empty messages.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Exit codes 97 through 99 are used by the thread library to signal
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internal synchronization errors between the main program and a
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proxy process that implements backgrounding.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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To avoid name conflicts with the underlying system, <i>atexit</i> and
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<i>atexitdont</i> are preprocessor macros defined as <i>p9atexit</i> and <i>p9atexitdont</i>;
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see <a href="../man3/intro.html"><i>intro</i>(3)</a>.<br>
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</table>
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<td width=20>
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<tr height=20><td>
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</table>
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<!-- TRAILER -->
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=15><td width=10><td><td width=10>
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<tr><td><td>
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<center>
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<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a>
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</center>
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</table>
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<!-- TRAILER -->
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